add zte k540 (#9)

devices/t31_lite_zte-k540/general/overlay/etc/builder.msg

@@ -0,0 +1,3 @@
+#
+Experimental system for building OpenIPC firmware for known devices
+#

devices/t31_lite_zte-k540/general/overlay/etc/wireless/usb

@@ -0,0 +1,12 @@
+#!/bin/sh
+
+set_gpio() {
+	[ "$2" -eq 1 ] && gpio set $1 || gpio clear $1
+	sleep 1
+}
+
+if [ "$1" = "atbm603x_wifi_usb" ]; then
+        set_gpio 51 0
+        modprobe atbm603x_wifi_usb
+        exit 0
+fi